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The parents of infants with neuromuscular disorders, most
often, infants with SMA types 1 and 2, are told that their
children will not survive infancy. Typically, these children
are well until a cold causes airway secretions to accumulate
in the lungs because of a weak cough mechanism. Bacteria
multiply in the secretions and the child develops pneumonia
and respiratory failure. After hospital admission, the
child is typically intubated (a tube is passed via the
nose or mouth into the lungs) for ventilatory support
and airway suctioning. Attempts to remove the tube usually
fail because the methods used to do so are appropriate
for children whose primary disorder is lung disease rather
than muscle weakness. Once extubation has failed, the
parents are told to either let the child die or to agree
to tracheotomy (placing a tube permanently in the neck
for ventilatory support and suctioning). We have found
that this is usually unnecessary when noninvasive inspiratory
and expiratory muscle aids are used appropriately.
Infants cannot air stack delivered volumes of air or
cooperate to receive maximal insufflations. All SMA
type 1 babies, SMA type 2 infants and others with infantile
neuromuscular weakness who have paradoxical chest wall
movement (inward movement of the chest when the belly
goes outward during inspiration), require nocturnal
high span bi-level positive airway pressure to prevent
pectus excavatum (chest deformity) and promote lung
growth. (See
article 143 Dr. Bach's Bibliography). Nocturnal
high span bi-level positive airway pressure prevents
or reverses pectus excavatum. It should be introduced
to the small child once he or she is asleep. The child
gradually becomes accustomed to it. Inspiratory pressures
should begin at 15 cm H2O and be gradually increased
to 18 to 20 cm H2O. Expiratory pressures should be left
at the minimum or 2 cm H2O. In addition to nocturnal
aid, deep insufflations are provided via oral-nasal
interface for children over 1 year of age along with
concomitant abdominal thrusts to prevent abdominal expansion
so as to direct the air into the upper chest. These
insufflations need to be timed to the child's inspirations.
Children can become cooperative with deep insufflation
therapy by 14 to 30 months of age.
We have routinely used MI-E via translaryngeal and
tracheostomy tubes in children with SMA under 1 year
of age. Although we have been using approximately the
same pressure settings as for adults, that is, +40 to
-40 cm H2O, its use through the very narrow gauge pediatric
tubes results in a severe pressure drop off that may
not permit the generation of optimal exsufflation flows.
However, even at these probably inadequate pressures
secretions are expulsed and dSaO2s reversed. The use
of MI-E via the upper airway can be effective for children
as young as 13 months of age. Children this young can
become accustomed to MI-E and permit its effective use
by not crying or closing their throats. Between two
and one-half and five years of age most children become
able to cooperate and cough on cue with MI-E and they
can then avoid hospitalizations and pneumonias during
their intercurrent chest infections. Exsufflation timed
abdominal thrusts are also used for infants.
Children too small to cooperate with manually and
mechanically assisted coughing or those who are not
introduced to these methods before a cold develops into
pneumonia and respiratory failure are hospitalized and
usually intubated (an catheter is passed via the nose
or mouth into the lungs for ventilatory support and
airway secretion evacuation). Often, each time that
small children develop chest infections until they are
old enough to cooperate will need to be hospitalized
and intubated. Our intensive
care protocol must be used to return these children
home without the need to do a surgical tracheostomy.
Patients using these methods as outpatients can also
avoid respiratory complications and hospitalizations
(see outpatient
protocol).
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